This invention relates to semiconductor processing of a microelectromechanical structure (MEMS) devices. MEMS devices include a wide range of devices that can serve a number of functions, such as, fluid ejectors, accelerometers, sensors, microphones, filters, light modulators and other such devices. The devices are typically on the scale of a few to many hundreds of micrometers in size. MEMS devices include micromechanical portions that have 3-dimensional features of various geometries, such as, walls, membranes, arms, as well as passages and trenches between the features. Semiconductor processing techniques, such as etching, grinding, polishing, bonding and depositing can be used to form a complex structure with multiple layers having different properties, materials or physical characteristics.